--> Abstract: Alternated Low and High-Density Turbidity Physical Experiments Highlighting Sediment Wave Formation Processes; #90063 (2007)

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Alternated Low and High-Density Turbidity Physical Experiments Highlighting Sediment Wave Formation Processes

 

Manica, Rafael1, Antonio Cosme Del Rey2, Richard Eduard Ducker1, Rogério Dornelles Maestri1, Ana Luiza de Oliveira Borges1 (1) Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil (2) Petrobras - Petroleo Brasileiro S.A, Vitoria, Brazil

 

In nature, most of turbidites sequences are generated by different events that had been being deposited throughout the years and consequently they present some peculiarities (e.g. grain size, thickness and bedforms) which difficult flow-deposit comprehension. In this way physical modelling has been employed as an alternative tool to understand it. Thus, the present work shows an experimental simulation of eighteen alternated low (5% concentration by volume) and high (15% concentration by volume) density turbidity currents in order to reproduce an analogue of these varied nature depositional packages. The deposit generated in each single alternated flow have created a morphologic substratum that interplayed with subsequent flow allowing the occurrence of erosion processes close the base of deposit (only high density current) and generating sediment waves whose migrating downstream (at proximal zones). At distal zone these effects were amortized and tabular layers were formed. The end member of this processes generate a lenticular sand bedding geometry. Yet, high-density currents present thicker deposits with massive gradation whereas low-density showed thinner deposits with predominance of normal graded bed. However, both flows present sediment waves formation with coarser grains at lee side and thicker deposits between its toepoint and troughpoint. The deposit package also shows similarity with sediment waves developed by natural overspill flows at meandering channels in mud-rich turbidites systems. Moreover, the small scale deposit analogous presented in this study is a new aspect concerning turbidity currents physical simulation proving the usefulness of this alternative tool in the geological interpretation studies.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California